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A transient shift in equatorial hydrology and vegetation during the Eocene Thermal Maximum 2

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Geoscience Frontiers 2024年第5期15卷 174-181页

作者： Gaurav Srivastava Harshita Bhatia Poonam Verma Yogesh P.Singh Shailesh Agrawal Torsten Utescher R.C.mehrotra Birbal Sahni Institute of Palaeosciences 53 University RoadLucknow 226007India Academy of Scientific and Innovative Research(AcSIR) Ghaziabad 201002India Senckenberg Research Institute and Natural History Museum Frankfurt/M.Senckenberg Research Station of Quaternary PalaeontologyWeimerGermany Institute for Geosciences University of BonnNussallee 853115 BonnGermany

The equatorial evergreen forests nourish the world’s biodiversity hotspots and are considered the lungs of the ***,their future survival is uncertain,due to anthropogenically increased carbon emissions and changes in the hydrological *** the changes in the hydrological cycle in the equatorial region due to an increase in carbon emission is of prime *** early Paleogene hyperthermal events are potential analogs to understand the consequences of high carbon emission on the hydrological *** this communication,we quantify the terrestrial seasonal climate using the plant proxy and infer that during the Eocene Thermal Maximum 2 when atmospheric carbon dioxide concentration was>1000 ppmv near the palaeo-equator(~0.6°N),the rainfall decreased significantly,leading to the expansion of deciduous *** study raises important questions about the future survival of equatorial rainforests and biodiversity hotspots under increased carbon emissions.

关键词： Coexistence approach Climate ETM-2 Global warming Hyperthermal Paleogene

Development and Validation of a Scaled Electric Combat Vehicle Tire Model

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World Journal of Engineering and Technology 2024年第1期12卷 24-39页

作者： Haniyeh Fathi Aricha.mehrotra Zeinab El-Sayegh Department of Automotive and Mechatronics Engineering Ontario Tech University Oshawa Canada

Pneumatic tire modeling and validation have been the topic of several research papers, however, most of these papers only deal with pneumatic passenger and truck tires. In recent years, wheeled-scaled vehicles have gained lots of attention as a feasible testing platform, nonetheless up to the authors’ knowledge there has been no research regarding the use of scaled tires and their effect on the overall vehicle performance characteristics. This paper presents a novel scaled electric combat vehicle tire model and validation technique. The pro-line lockdown tire size 3.00 × 7.35 is modeled using the Finite Element Analysis (FEA) technique and several materials including layered membrane, beam elements, and Mooney-Rivlin for rubber. The tire-rim assembly is then described, and the rigid body analysis is presented. The tire is then validated using an in-house custom-made static tire testing machine. The tire test rig is made specifically to test the pro-line tire model and is designed and manufactured in the laboratory. The tire is validated using vertical stiffness and footprint tests in the static domain at different operating conditions including several vertical loads. Then the tire is used to perform rolling resistance and steering analysis including the rolling resistance coefficient and the cornering stiffness. The analysis is performed at different operating conditions including longitudinal speeds of 5, 10, and 15 km/h. This tire model will be further used to determine the tractive and braking performance of the tire. Furthermore, the tire test rig will also be modified to perform cornering stiffness tests.

关键词： Tire Modeling Tire Testing Machine Vehicle Dynamics Unmanned Vehicle Modeling Finite Element Analysis Tire Mechanics

Local feature based retrieval approach for iris biometrics

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Frontiers of Computer Science 2013年第5期7卷 767-781页

作者： Hunny mehrotra Banshidhar MAJHI Department of Computer Science and Engineering National Institute of Technology Rourkela 769008 India

This paper proposes an efficient retrieval ap- proach for iris using local features. The features are extracted from segmented iris image using scale invariant feature trans- form （SIFT）. The keypoint descriptors extracted from SIFT are clustered into m groups using k-means. The idea is to perform indexing of keypoints based on descriptor property. During database indexing phase, k-d tree k-dimensional tree is constructed for each cluster center taken from N iris im- ages. Thus for m clusters, rn such k-d trees are generated de- noted as ti, where 1 ~〈 i ~〈 m. During the retrieval phase, the keypoint descriptors from probe iris image are clustered into m groups and ith cluster center is used to traverse correspond- ing ti for searching, k nearest neighbor approach is used, which finds p neighbors from each tree （ti） that falls within certain radius r centered on the probe point in k-dimensional space. Finally, p neighbors from m trees are combined using union operation and top S matches （S c_ （m x p）） correspond- ing to query iris image are retrieved. The proposed approach has been tested on publicly available databases and outper- forms the existing approaches in terms of speed and accuracy.

关键词： Indexing SIFT k-means k-d tree k nearest neighbors iris biometrics

Repetitive Sequences in Plant Nuclear DNA:Types, Distribution, Evolution and Function

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Genomics, Proteomics & Bioinformatics 2014年第4期12卷 164-171页

作者： Shweta.mehrotra Vinod Goyal Department of Botany University of Delhi

Repetitive DNA sequences are a major component of eukaryotic genomes and may account for up to 90% of the genome size. They can be divided into minisatellite, microsatellite and satellite sequences. Satellite DNA sequences are considered to be a liist-evolving component of eukaryotic genomes, comprising tandemly-arrayed, highly-repetitive and highly-conserved monomer sequences. The monomer unit of satellite DNA is 150M00 base pairs （bp） in length. Repetitive sequences may be species- or genus-specific, and may be centromeric or subtelomeric in nature. They exhibit cohesive and concerted evolution caused by molecular drive, leading to high sequence homogeneity. Repetitive sequences accumulate variations in sequence and copy number during evolution, hence they are important tools for taxonomic and phylogenetic studies, and are known as ＂tuning knobs＂ in the evolution. Therefore, knowledge of repetitive sequences assists our understanding of the organization, evolution and behavior of eukaryotic genomes. Repetitive sequences have cytoplasmic, cellular and developmental effects and play a role in chromosomal recombination. In the post-genomics era, with the introduction of next-generation sequencing tech- nology, it is possible to evaluate complex genomes for analyzing repetitive sequences and decipher- ing the yet unknown functional potential of repetitive sequences.

关键词： Repetitive Satellites Tandem Dispersed Concertedsequences evolution Next-generation sequencing

Legumes from the Paleocene sediments of India and their ecological significance

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Plant Diversity 2023年第2期45卷 199-210页

作者： Harshita Bhatia Gaurav Srivastava R.C.mehrotra Birbal Sahni Institute of Palaeosciences 53 University RoadLucknow 226007India Academy of Scientific and Innovative Research(AcSIR) Ghaziabad 201002India

During the early Paleogene,greenhouse gases created warm global *** warm climates redistributed the habitat of marine and terrestrial biota *** the ecology of biotas under extremely warm climates is important to decipher their behavior in future climate *** we report two new legume fossils(Leguminocarpum meghalayensis Bhatia,Srivastava et mehrotra ***.,and Parvileguminophyllum damalgiriensis Bhatia,Srivastava et mehrotra ***.) from the late Paleocene sediments of Tura Formation of Meghalaya,northeast ***,the Paleocene legume fossil records indicate that legumes most likely immigrated to India from Africa via the Ladakh-Kohistan Arc during the early ***,previously reconstructed climate data from the Tura Formation indicate that legumes were well adapted to a warm seasonal climate with monsoon rains.

关键词： Fabaceae Global warming Fruits Damalgiri Tura Rhynchosia

Determination of Some Ethnomedicinally Important Constituents of Aegle marmelos Fruit During Different Stages of Ripening

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中国天然药物 2011年第3期9卷 204-209页

作者： Nisha Yadav Parul Singh Ranjana.mehrotra Quantum Optics and Photon Physics National Physical Laboratory(Council of Scientific and Industrial Research)K.S.Krishnan MargNew Delhi 110012India

AIM:Aegle marmelos is a medicinal herb belonging to the Rutacae *** fruit of *** at each stage of ripening is used as ethnomedicine to cure various *** aim of the present study was to determine the components contributing to the medicinal value of the *** fruit at different stages of ***:High-performance liquid chromatography(HPLC)was used to determine polyphenol,vitamins,organic acids and sugars in *** fruit at different stages of ***:Tannin,a polyphenol responsible for astringent and antimicrobial properties of *** fruit was found to increase during ***,a vital medicinal component was detected in traceable amount only in full-ripe *** ***-vin contributes towards body growth,reproduction and red cell *** content of ascorbic acid(vitamin C)which is useful in preventing scurvy decreased significantly as fruit ***:The difference in the medicinal effect of *** fruit at each stage of ripening might be due to the presence of different amount of polyphenol,vitamins and organic acids.

关键词： Aegle marmelos Ripening HPLC Tannin Vitamins

Cenozoic flora of western India and its significance in palaeoclimatic and palaeophytogeographic interpretation

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科学通报 2013年第S1期58卷 134-141页

作者： SHUKLA Anumeha.mehrotra Rakesh Chandra Birbal Sahni Institute of Palaeobotany

The Cenozoic flora of western India(Rajasthan and Gujarat) is adversely affected by the tectonic activity such as collision of the Indian subcontinent with the Eurasian plate which is responsible for the Himalayan and Tibetan Plateau uplift. This collision and its resultants affected the ubiquitous tropical lowland vegetation of the Indian subcontinent(including western India) and are responsible for different types of topographic regions as seen today in the Indian subcontinent. The region is important as it has witnessed a drastic change in climate of the region since the Cenozoic time and also provided opportunities to the western and eastern flora to intermingle. The main basins in western India comprising Cenozoic sequences are: Bikaner-Nagaur, Jaisalmer and Barmer in Rajasthan and Kachchh, Mainland and Saurashtra in Gujarat. These basins are very rich in lignite which is the main source of electric power generation in western India. This lignite is mainly of Eocene in age. The Cenozoic flora of western India was almost tropical growing in well drained areas as compared to arid to sub-humid regions with xeric vegetation today. The reported fossils are represented by leaves, woods, fruits and seeds. The leaves are abundant in the Palaeogene as compared to the Neogene. The Neogene period can be marked by the abundant legumes and dipterocarpaceous remains. The important families viz., Anacardiaceae, Annonaceae, Arecaceae, Calophyllaceae, Clusiaceae, Combretaceae, Euphorbiaceae, Flacourtiaceae, Icacinaceae, Lauraceae, Lythraceae, Meliaceae, Moraceae, Myrtaceae, Pandanaceae and Sonneratiaceae have been reported from the Palaeogene sediments, whereas Anacardiaceae, Araucariaceae, Arecaceae, Combretaceae, Dipterocarpaceae, Fabaceae, Lauraceae, Lecythidaceae, Lythraceae, Malvaceae, Meliaceae, Moraceae, Podocarpaceae, Rhamnaceae, Rhizophoraceae, Rutaceae, Sapindaceae and Sonneratiaceae are known from the Neogene sediments. All the recovered elements strongly indicate th

关键词： megafossil Rajasthan Gujarat palaeoclimate phytogeography

Low latitude floral assemblage from the Late Oligocene sediments of Assam and its palaeoclimatic and palaeogeographic significance

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科学通报 2013年第S1期58卷 156-161页

作者： SRIVASTAVA Gaurav mehrotra Rakesh Chandra Birbal Sahni Institute of Palaeobotany

There are many outcrops of the Tertiary sediments in northeast India and a large number of plant megafossils have been described from there. Among all, the Late Oligocene sedimentary basin of Makum Coalfield is very important because there is no other exposure having such a rich palaeofloral assemblage not only from northeast India but also from the whole country. The assemblage is also important to confirm whether the suturing between the Indian and Eurasian plates was complete to facilitate plant migration or not. All the reported plant fossils clearly indicate the prevalence of tropical climate in the region during the deposition of the sediments. As the majority of taxa occur in tropical evergreen to moist deciduous and littoral and swampy forest, a warm and humid climate may be envisaged in Upper Assam during the Late Oligocene. The abundance of palms and pantropical megathermal plant families in the Makum Coalfield indicate that the cold month mean temperature(CMMT) was not less than 18°C. The quantitative palaeoclimate reconstruction indicates a monsoonal climate during the period with the same intensity as that of the modern day. The absence of Southeast Eurasian elements in the fossil assemblage provides clear evidence that suturing between the Indian and Asian plates was not complete till the Late Oligocene. Several modern analogues of the fossil taxa are now endemic to the Western Ghats which lies in the same palaeolatitude.

关键词： northeast India Makum Coalfield megafossil monsoon

Differential Effects of Butyric Acid on Mouse Skin Tumorigenesis

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Biomedical and Environmental Sciences 1997年第4期10卷 436-441页

作者： KRISHNAP·GUPTA N·K·mehrotra EnvironmentalCarcinogenesisLaboratory IndustrialToxicologyResearchCentre EnvironmentalCarcinogenesisL

We studied the effects of butyric acid (BA) on mouse skin tumorigenesis using chronicanimal bioassays. Topical application of BA immediately after each treatment with 12-0-te-t radecanoyl phorbol-13-acetate (TPA) promoter' inhi bi ted skint umors. The effect was depe n -dent on the dose of BA applied. BA showed no marked inhibitory effect on either skin tumorinitiation or complete tumorigenesis induced by dimet hyl benzant hracene (DMBA ). Si nce t u -mor promotion reportedly involves epigenetic events whereas tumor initiation or complete tu-morigenesis takes place through genetic pathways, it is Possible that BA exerts its antitumori-genic effects mainly by altering the epigenetic events responsible for tumor promotion. The re-sults of the study could further be used to study the mechanism of action and modification ofantitumorigenic effects of BA in combination with other substances

关键词： DMBA Differential Effects of Butyric Acid on Mouse Skin Tumorigenesis